1. Field of the Invention
The present invention relates to a chip package, and more particularly to a light emitting diode (LED) package.
2. Description of Related Art
Due to numerous advantages of long life span, miniature size, high vibration and shock resistance, low heat generating, low power consumption and so on, light emitting diodes (LEDs) have been widely applied to indicating lights or light sources employed in a variety of household electric appliances and instruments. With recent development towards multicolor and high illumination, the applications of the LEDs are extended to large-sized outdoor billboards, traffic lights, etc. In the future, the LEDs may become the power-saving and environment-friendly light sources in replacement of tungsten lamps and mercury vapor lamps.
Please refer to FIG. 1. A conventional LED package 100 includes a lead frame 110, an LED chip 120, a transparent encapsulant 130, a transparent cap 140, and two bonding wires 150.
The lead frame 110 includes an electrically isolated body 112, two leads 114 and a heat sink 116. The electrically isolated body 112 encapsulates a part of the heat sink 116 and a part of each of the leads 114. The LED chip 120 is disposed on the heat sink 116 and is electrically connected to the two leads 114 through the two bonding wires 150. The electrically isolated body 112 includes a trench 112a exposing a part of each of the leads 114 and the two bonding wires 150, and the trench 112a leads to an easy assembling of the transparent cap 140 with the electrically isolated body 112. The transparent encapsulant 130 is positioned between the transparent cap 140 and the lead frame 110 to encapsulate and protect the LED chip 120 and the two bonding wires 150.
According to the related art, the transparent cap 140 is firstly formed and then assembled and mounted to the electrically isolated body 112. During assembling, a vacuum process performed between the transparent cap 140 and the lead frame 110 is required, such that the transparent encapsulant 130 is injected. However, said vacuum process does not result in a perfect vacuum between the transparent cap 140 and the leadframe 110, and thus some air still remains in the transparent encapsulant 130, which adversely affects the optical performance of the LED package 100.
To overcome the aforesaid drawbacks, in another conventional LED package, the transparent encapsulant is formed on the leadframe through directly performing an injection molding process in absence of disposing the transparent cap. Nevertheless, due to the small size of the LED package, a nozzle required in the injection molding process is not apt to be disposed. Moreover, given that the material of the transparent encapsulant is silica gel, the transparent encapsulant should be formed through a thermal curing process instead of the injection molding process.